1. Field of the Invention
This invention relates to a display device which displays image information in the form of an array of a plurality of pixels, and more particularly, to a display device having a mechanical structure which allows rewrites of images.
2. Description of the Related Art
Display devices for exhibiting image information formed with an array of a plurality of pixels includes a non-light emitting display device without an light-emitting means. The non-light emitting display device is widely used in large-screen displays to exploit its energy-saving advantage resulting from not including any light-emitting means. A typical type of such a large non-light emitting display device includes a magnetic rotary display device in which spheres or cubes with differently-colored sides are arranged in correspondence with pixels and are magnetically rotated to switch their exposed faces, thereby representing their respective pixels. There is also a similar type in which micro capsules containing magnetic material are magnetically moved and rotated to represent their respective pixels.
In these types, however, the exposed faces of the spheres, cubes, micro capsules or the like are switched to represent the respective pixels, resulting in the display of limited colors, usually four colors.
As a solution to the problems with these types, Japanese Patent Laid-Open Publication No. SHO-56-150786 presents a color film display device having a plurality of color films stacked on one another for display. This display device has a means for sliding the color films, configured to utilize attraction and repulsion between permanent magnets and electromagnets or configured to mechanically slide the color films with a rotating wheel brought into contact therewith.
The sliding means of these configurations cannot independently slide one of the stacked color films. The combination of multiple sliding operations is thus required to slide a film to an intermediate position. Further, the configuration utilizing magnetic force requires highly precise control of electromagnetic force, causing difficulty in fixing the color films in their respective accurate positions and the possibility of interference with a color film in an adjacent display unit. Further, the mechanical sliding configuration requires the provision of another mechanical sliding means facing the front display surface, resulting in a complicated structure.
The present inventors have presented a actuated film display device of a type in which color films are mounted to the distal ends of cantilevers which are displaced by electrostatic force to slide the color films (e.g., Japanese Patent Laid-Open Publication No. HEI-8-271933).
This actuated film display device of the cantilever structure has, as shown in FIG. 1, fixed films 91 colored white, for example, placed in a tiled roof-like arrangement, and actuated films 92 colored black or another color to be moved out through the gaps. The fixed films 91 are fixed by first support films 93. The actuated films 92 are attached on second support films 94. The second support films 94 are selectively bent by use of electrostatic force generated with fixed electrodes 95 to change a display image.
Although the above type of display device utilizing electrostatic force as driving force, being configured to apply voltage between the individual second support films and the fixed electrodes, is effective for the display type of switching the display pixels individually or simultaneously, the resulting wiring of electrodes is complicated. Further, the above type requires the stable maintenance of the potential of each electrode in order to maintain the display of a fixed image, resulting in an increase in consumption power.
For a display device displaying fixed image information such as tariffs and schedules in stations for a long time with very low frequency of rewriting of the image information, a more simple and power-saving image rewriting means is required.